Licenses: Creative Common
Human echolocation is a learned ability for humans to sense their environment from echoes.
This ability is used by some blind people to navigate their environment and sense their surroundings in detail.
Studies in 2010 and 2011 using functional magnetic resonance imaging techniques have shown that parts of the brain associated with visual processing are adapted for the new skill of echolocation (Kupers et al., 2010; Thaler, Arnott and Goodale, 2011).
Studies with blind patients, for example, suggest that the click-echoes heard by these patients were processed by brain regions devoted to vision rather than audition (Thaler, Arnot and Goodale, 2011).
Neuroplasticity is most active in childhood as a part of normal human development, and can also be seen as an especially important mechanism for children in terms of risk and resiliency (Masten, 2011).
Trauma is considered a great risk as it negatively affects many areas of the brain and puts strain on the sympathetic nervous system from constant activation.
Trauma thus alters the brain’s connections such that children who have experienced trauma may be hypervigilant or overly aroused (Schore, 2001).
However, a child’s brain can cope with these adverse effects through the actions of neuroplasticity (Cioni, D’Acunto and Guzzetta, 2011).
In a single lifespan, individuals of an animal species may encounter various changes in brain morphology.
Many of these differences are caused by the release of hormones in the brain and others are the product of evolutionary factors or developmental stages (Parry et al., 1997; Parry, Goldsmith, 1993; Wayne et al., 1998; Wayne et al., 1998; Hofman and Swaab; 1992).
Some changes occur seasonally in species to enhance or generate response behaviours.
Seasonal brain changes:
Changing brain behaviour and morphology to suit other seasonal behaviours is relatively common in animals.
These changes can improve the chances of mating during breeding season (Parry et al., 1997; Parry, Goldsmith, 1993; Wayne et al., 1998; Nottebohm, 1981; Taklami, Urano, 1984; Xiong et al., 1997).
Examples of seasonal brain morphology change can be found within many classes and species.
Within the class Aves, black-capped chickadees experience an increase in the volume of their hippocampus and strength of neural connections to the hippocampus during fall months (Barnea and Nottebohm, 1994; Smulders et al., 1995).
These morphological changes within the hippocampus which are related to spatial memory are not limited to birds, as they can also be observed in rodents and amphibians.
In songbirds, many song control nuclei in the brain increase in size during mating season (Nottebohm, 1981).
Among birds, changes in brain morphology to influence song patterns, frequency, and volume are common (Smith, 1996).
Gonadotropin-releasing hormone (GnRH) immunoreactivity, or the reception of the hormone, is lowered in European starlings exposed to longer periods of light during the day (Parry et al., 1997; Parry and Goldsmith, 1993).
The California sea hare, a gastropod, has more successful inhibition of egg-laying hormones outside of mating season due to increased effectiveness of inhibitors in the brain (Wayne, et al., 1998).
Changes to the inhibitory nature of regions of the brain can also be found in humans and other mammals (Hofman and Swaab, 1992).
In the amphibian Bufo japonicus, part of the amygdala is larger before breeding and during hibernation than it is after breeding (Takami and Urano, 1984).
Seasonal brain variation occurs within many mammals.
Part of the hypothalamus of the common ewe is more receptive to GnRH during breeding season than at other times of the year (Xiong et al., 1997).
Humans experience a change in the “size of the hypothalamic suprachiasmatic nucleus and vasopressin-immunoreactive neurons within it”, during autumn/fall, when these parts are larger (Hofman and Swaab, 1992).
In the spring, both reduce in size (Tramontin and Brenowitz, 2000).
Several companies have offered so-called cognitive training software programs for various purposes that claim to work via neuroplasticity; one example is Fast ForWord which is marketed to help children with learning disabilities.
A systematic meta-analytic review, however, found that “There is no evidence from the analysis carried out that Fast ForWord is effective as a treatment for children’s oral language or reading difficulties” (Strong, et al., 2011).
A 2016 review found very little evidence supporting any of the claims of Fast ForWord and other commercial products, as their task-specific effects fail to generalise to other tasks (Simons et al., 2016).
Reviews of MRI studies on people with ADHD suggest that the long term treatment of attention deficit hyperactivity disorder (ADHD) with stimulants, e.g. amphetamine or methylphenidate, decreases abnormalities in brain structure and function found in subjects with ADHD and improves function in several parts of the brain, such as the right caudate nucleus of the basal ganglia (Hart et al., 2013; Spencer et al., 2013; Frodl and Skokauskas, 2012).
A number of studies have linked meditation practice to differences in cortical thickness or density of gray matter (Sasmita et al, 2018; Pagnoni et al., 2007; Vestergaard-Poulsen et al., 2009; Luders et al., 2009).
One of the most well known studies to demonstrate this was led by Sara Lazar, from Harvard University, in 2000.
Richard Davidson, a neuroscientist at the University of Wisconsin, has led experiments in cooperation with the Dalai Lama on effects of meditation on the brain.
His results suggest that long term or short term practice of meditation results in different levels of activity in brain regions associated with such qualities as attention, anxiety, depression, fear, anger and the ability of the body to heal itself.
These functional changes may be caused by changes in the physical structure of the brain (Lutz et al., 2004; Begley, 2007; Davidson and Lutz, 2008; Frith, 2007).
Fitness and Exercise
Aerobic exercise promotes adult neurogenesis by increasing the production of neurotrophic factors (compounds that promote growth or survival of neurons), such as brain derived neurotrophic factor (BDNF), insulin-like growth factor 1 (IGF-1), and vascular endothelial growth factor (VEGF) (Tarumi and Zhang, 2014; Szuhany, Bugatti and Otto, 2014; Gomez-Pinilla and Hillman, 2013).
Exercise-induced neurogenesis in the hippocampus is associated with measurable improvements in spatial memory (Erickson, Leckie and Weinstein, 2014; Erickson, Miller and Roecklein, 2012; Less and Hopkins, 2013; Carvalho et al., 2014).
Consistent aerobic exercise over a period of several months induces marked clinically significant improvements in executive function (i.e., the “cognitive control” of behaviour) and increased gray matter volume in multiple brain regions, particularly those that give rise to cognitive control (Erickson and Miller, 2012; Gomez-Pinilla and Hillman, 2013; Erickson, Leckie and Weinstein, 2014; Guiney and Machado, 2013; Buckley et al., 2014).
Higher physical fitness scores (measured by VO2 max) are associated with better executive function, faster processing speed, and greater volume of the hippocampus, caudate nucleus, and nucleus accumbens (Erickson, Leckie and Weinstein 2014).